The present invention relates to a laminated core arrangement for an electric machine and to an electric machine with such a laminated core arrangement.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Servo motor armatures are known to have a polygonal laminated core which is equipped around the entire circumference with permanently-excited small plate magnets and is bandaged with a glass fiber tape. The laminated core in such cases has two end sides: a drive side (drive end) and a brush side (non-drive end). In particular an end sheet, which is usually larger than the remaining sheets, is provided at one of the end sides. Such armatures are subsequently magnetized at an angle.
However such an arrangement also has disadvantages. In particular pole gaps are encountered between the poles magnetized at an angle. Since the armature is provided with magnets over the entire circumference this results in magnet material which is unmagnetized.
It is also known to save unused magnet material by pole gaps which are unequipped. The armature is hereby constructed in stages, i.e. the laminated core has at least two part cores in the axial direction behind one another, which are rotated in relation to one another. In this construction the part cores are designed large enough for the magnets with maximum dimensions to be able to be attached. This means that the overall core must be lengthened since otherwise the magnets would collide with the edges at the transition of the individual part cores. Since not all magnets have the maximum possible size, this layout produces gaps between the individual magnets. This leads, in turn, in the subsequent bandaging process to enabling the bandage to be drawn in between the magnets and thereby cause displacement of individual magnets. This adversely affects electromagnetic values of the motor.
It would therefore be desirable and advantageous to provide an improved laminated core arrangement and improved electric machine to obviate prior art shortcomings and to have compact design while yet being reliable in operation.